1. Field of the Invention
The present invention relates to a vibration correction apparatus, a lens apparatus using the vibration correction apparatus, and an optical apparatus using the lens apparatus.
2. Related Background Art
In current cameras, all important operations for photography, e.g., exposure determination and focusing, are automated. For this reason, even unskilled photographers rarely make photographic errors.
In addition, recently, systems for preventing hand vibrations from being applied to cameras have been studied, thus almost eliminating factors that cause photographers to make photographic errors.
A system for preventing hand vibrations will be briefly described below.
In general, hand vibrations applied to a camera at the time of photography have a frequency of 1 to 12 Hz. According to the basic idea for taking a picture without image blur even with such hand vibrations at the time of shutter release, the vibrations of the camera due to the above hand vibrations must be detected, and the correction lens must be displaced in accordance with the detection value. In order to allow a photographer to take a picture without image blur even with vibrations produced in the camera, the vibrations of the camera must be accurately detected first, and then optical axis displacement due to hand vibrations must be corrected.
Detection of such vibrations (camera vibrations), according to its principle, can be performed by equipping the camera with a vibration sensor for detecting an angular acceleration, angular velocity, angular displacement, or the like and a vibration detection means for electrically or mechanically integrating output signals from the vibration sensor to output an angular displacement. A correction optical apparatus for decentering the photography optical axis is driven on the basis of this detection information, thereby suppressing vibrations.
A system having a vibration correction function will be briefly described below with reference to FIG. 5.
FIG. 5 shows a system for suppressing image blur caused by vertical camera vibration 81p and horizontal camera vibration 81y in the directions indicated by arrows 81. In this case, this system is provided for the exchangeable photographing lens of a single-lens reflex camera.
Referring to FIG. 5, this camera includes a lens barrel 82, vibration sensors 83p and 83y for respectively detecting vertical camera vibration and horizontal camera vibration in vibration detection directions 84p and 84y, and a vibration correction apparatus 85 (having coils 87p and 87y each serving to apply thrust to the vibration correction apparatus 85 and position sensors 86p and 86y for detecting the position of the vibration correction apparatus 85). A position control loop is formed in the vibration correction apparatus 85, which is driven in accordance with a target value based on outputs from the vibration sensors 83p and 83y, thereby ensuring stability of an image surface 88.
In general, a photographer uses a camera in all positions, e.g., upward and downward positions, at the time of photography. Assume that a photographing lens including an image blur correction apparatus made up of a vibration correction apparatus and vibration sensors like those shown in FIG. 5 is mounted in a camera body, and photography is performed. In this case, since a tilt occurs in the optical axis direction due to the weight of the vibration prevention optical element (correction lens), the optical element must be decentered in the optical axis direction by a charge spring or the like.
The friction on the contact surface due to the charged state (i.e., the decentered state) increases to result in a deterioration in the movement of the optical element.
It is an object of the present invention to provide an image blur correction apparatus which can improve a vibration correction effect by performing drive so as to reduce the influence of a frictional force in driving a correction lens.
In order to achieve the above object, according to the present invention, there is provided a vibration correction apparatus comprising
a vibration detection unit which detects a vibration,
a signal processing unit which performs signal processing for a vibration detection signal output from the vibration detection unit,
a vibration correction unit which corrects an image movement caused by the vibration, on the basis of a drive signal output from the signal processing unit, and
a controller which controls drive of the vibration correction unit,
wherein the controller corrects the drive signal from the signal processing unit by using a predetermined correction value corresponding to a drive direction of the vibration correction unit, and controls drive of the vibration correction unit by using the corrected drive signal.
In order to achieve the above object, according to the present invention, there is provided a vibration correction apparatus comprising
a vibration detection unit which detects a vibration,
a signal processing unit which performs signal processing for a vibration detection signal output from the vibration detection unit,
a vibration correction unit which corrects an image movement caused by the vibration, on the basis of a drive signal output from the signal processing unit, and
a controller which controls drive of the vibration correction unit,
wherein the controller corrects the drive signal from the signal processing unit by using a predetermined correction value corresponding to a polarity of a vibration detection signal output from the vibration detection unit, and controls drive of the vibration correction unit by using the corrected drive signal.
In order to achieve the above object, according to the present invention, there is provided an interchangeable lens apparatus which is detachably mounted on an image pickup apparatus, comprising
a vibration detection unit which detects a vibration,
a signal processing unit which performs signal processing for a vibration detection signal output from the vibration detection unit,
a vibration correction optical unit which corrects an image movement caused by the vibration, on the basis of a drive signal output from the signal processing unit, the vibration correction optical unit being mounted in a main body of the interchangeable lens apparatus and capable of moving in a direction perpendicular to an optical axis of the interchangeable lens apparatus, and
a controller which controls drive of the vibration correction unit,
wherein the controller corrects the drive signal from the signal processing unit by using a predetermined correction value corresponding to a drive direction of the vibration correction optical unit, and controls drive of the vibration correction optical unit by using the corrected drive signal.
In order to achieve the above object, according to the present invention, there is provided an interchangeable lens apparatus which is detachably mounted on an image pickup apparatus, comprising
a vibration detection unit which detects a vibration,
a signal processing unit which performs signal processing for a vibration detection signal output from the vibration detection unit,
a vibration correction optical unit which corrects an image movement caused by the vibration, on the basis of a drive signal output from the signal processing unit, the vibration correction optical unit being mounted in a main body of the interchangeable lens apparatus and capable of moving in a direction perpendicular to an optical axis of the interchangeable lens apparatus, and
a controller which controls drive of the vibration correction unit,
wherein the controller corrects the drive signal from the signal processing unit by using a predetermined correction value corresponding to a polarity of a vibration detection signal output from the vibration detection unit, and controls drive of the vibration correction optical unit by using the corrected drive signal.
In order to achieve the above object, according to the present invention, there is provided an optical apparatus including an interchangeable lens and an image pickup apparatus which allows the interchangeable lens apparatus to be detachably mounted thereon and picks up photography light from the interchangeable lens apparatus, comprising
a vibration detection unit which detects a vibration,
a signal processing unit which performs signal processing for a vibration detection signal output from the vibration detection unit,
a vibration correction optical unit which corrects an image movement caused by the vibration, on the basis of a drive signal output from the signal processing unit, the vibration correction optical unit being mounted in a main body of the interchangeable lens apparatus and capable of moving in a direction perpendicular to an optical axis of the interchangeable lens apparatus,
a controller which controls drive of the vibration correction unit, and
an image pickup device which picks up photography light from the interchangeable lens apparatus,
wherein the controller corrects the drive signal from the signal processing unit by using a predetermined correction value corresponding to a drive direction of the vibration correction optical unit, and controls drive of the vibration correction optical unit by using the corrected drive signal.
In order to achieve the above object, according to the present invention, there is provided an optical apparatus including an interchangeable lens and an image pickup apparatus which allows the interchangeable lens apparatus to be detachably mounted thereon and picks up photography light from the interchangeable lens apparatus, comprising
a vibration detection unit which detects a vibration,
a signal processing unit which performs signal processing for a vibration detection signal output from the vibration detection unit,
a vibration correction optical unit which corrects an image movement caused by the vibration, on the basis of a drive signal output from the signal processing unit, the vibration correction optical unit being mounted in a main body of the interchangeable lens apparatus and capable of moving in a direction perpendicular to an optical axis of the interchangeable lens apparatus,
a controller which controls drive of the vibration correction unit, and
an image pickup device which picks up photography light from the interchangeable lens apparatus,
wherein the controller corrects the drive signal from the signal processing unit by using a predetermined correction value corresponding to a polarity of a vibration detection signal output from the vibration detection unit, and controls drive of the vibration correction optical unit by using the corrected drive signal.
Furthermore, the vibration correction unit may be an optical correction unit including a correction optical device which has an optical axis and is moved in a direction perpendicular to the optical axis.
The controller may correct the drive signal by adding or subtracting a predetermined correction value corresponding to the drive direction of the vibration correction unit to or from the drive signal from the signal processing unit.
The correction value may be one of a plurality of predetermined correction values, and the plurality of correction values may be stored in a memory.
The signal processing unit may include a calculation part which obtains a displacement signal by integrating the vibration detection signal output from the vibration detection unit.
Moreover, the vibration detection signal output from the vibration detection unit is the vibration angular velocity signal, and the signal processing unit may include a calculation part which obtains a displacement signal by integrating the angular velocity signal.
The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description in conjunction with the accompanying drawings and the appended claims.